Grav-Jump

This is a short, but pretty solid game. The concept is simple and encourages good use of resource management. The gameplay is technically sound. There is one bug that I managed to come across, although it might be an intentional feature, but whenever you press the jump button and left click at the same time, you get boosted up much farther in the air than you normally would, which can be used to get to the top quickly and collect a far more batteries on your way down without using up nearly as much. I tested this and was able to have 52 batteries left over by the end using this method as opposed to the usual method in which I was only able to get around 34. As mentioned before, I don't know if this is intentional or not, seeing as it wasn't pointed out in the help section, but if it is, then you can just ignore this.
The only other real criticism that I can think of is the lack of levels. I think that there could be some unique things done with this concept, like maybe having obstacles that would guard a path that had more batteries, providing a sense of risk vs reward, or branching paths to take on your way up, giving the player more than one way to tackle the level and providing a bit of extra replayability.
Other than those two things, I actually think that this game is pretty good. This gets a thumbs up from me.

I like this idea very much! Too bad there are no more levels and other special stuff.

Very nice game you have here!